Well Zelda breath of the wild looks excellent even today, with 900p and stable 30 fps being a launch title. Mario Odissey looks gorgeous too, but now both have been topped by Luigi's Mansion 3, damn it looks really good. Then you have Astral chain, the jaw dropping Port of the Witcher 3, the cute remake of Link's Awakening, smash ultimate at 1080p and stable 60 fps with all the action, Bayonetta 2 looks amazing even when it wasn't designed for switch hardware, dragon quest xi looks amazing in both 3d and 2d modes, the good old Skyrim, the excellent Port of db fighterz, and the list goes on.

I'm having high expectations for Bayonetta 3 and breath of the wild 2, I think those 2 will end up being the best looking games on the switch at the end of it's lifespan, maybe Metroid prime 4 as well. We'll see!

Breath of the Wild and DOOM are still on top for me.

I’d probably say the best to look at is still Breath of the Wild, but Astral Chain does an amazing job and is definitely imo the best looking Switch game released this year.

Just beat it the other day (finally)
Was extremely fun, will probably go back to it at some point.

Luigi's Mansion 3, Alien Isolation, Mario + Rabbids: Kingdom Battle, Cuphead, Ori and the Blind Forest, Link's Awakening, BotW, and Astral Chain.

both Zelda games.

Mario Odyssey and Xenoblade 2 look very pretty and glitzy overall, Octopath in terms of style.

To me the biggest wow factor came with Breath of the Wild.  It's because I could stand someplace like the starting plateau and see Death Mountain in the distance.  But then later I could actually explore and interact with Death Mountain.  None of the visuals were fake backgrounds like being on a movie set.  I could see things on the far end of this huge world and they were actually real things I could experience.

Luigi's mansion 3. The lighting, shadows, animations and sharp 1080p image make it the most impressive looking game on switch. As far as large scale games with a huge world go i would say DQ11s has prettier visuals than breath of the wild in many area's but they are spoiled by lots of pop in, so BOTW is still the standard for open world on switch.

On a purely technical level probably Witcher 3 despite all the downgrades from the other versions. It's the sort of high-end port everyone thought was impossible on Switch, a vast open world game that already pushed the PS4 and XB1 at 30 FPS. Somehow it still looks like the Witcher 3 and runs basically as well as any other console version. Even Doom and Wolfenstein 2 aren't as impressive since they are linear shooters.

Dragon Quest 11 is the best overall port since you really have to put it side by side with the PS4 version to notice the downgrades and what downgrades there are don't diminish the fact that it is really the definitive edition.

For Switch exclusives it's much harder to narrow down. BOTW, Mario Odyssey, Mario Kart 8, all look amazing thanks to a combination of stellar tech and art direction. Luigi's Mansion 3 I guess would be best on a technical level simply because it's newer and therefore the team was better able to maximize the hardware, but I think art-wise I prefer many games over it.

I still believe Breath of the Wild looks very good.
Other games would be Hollow Knight and Xenoblade 2.